J/ApJS/247/9 FGK stars magnetic activity in LAMOST-Kepler field (Zhang+, 2020)
Magnetic activity of F-, G-, and K-type stars in the LAMOST-Kepler field.
Zhang J., Bi S., Li Y., Jiang J., Li T., He H., Yu J., Khanna S., Ge Z.,
Liu K., Tian Z., Wu Y., Zhang X.
<Astrophys. J. Suppl. Ser., 247, 9 (2020)>
=2020ApJS..247....9Z 2020ApJS..247....9Z
ADC_Keywords: Spectra, optical; Abundances, [Fe/H]; Effective temperatures;
Stars, dwarfs; Stars, F-type; Stars, G-type; Stars, K-type
Keywords: Stellar activity ; Stellar atmospheres ; Stellar chromospheres ;
Stellar magnetic fields
Abstract:
Monitoring chromospheric and photospheric indexes of magnetic activity
can provide valuable information, especially the interaction between
different parts of the atmosphere and their response to magnetic
fields. We extract chromospheric indexes, S and RHK+, for 59816
stars from LAMOST spectra in the LAMOST-Kepler program, and
photospheric index, Reff, for 5575 stars from Kepler light curves. The
log Reff shows positive correlation with logRHK+. We estimate the
power-law indexes between Reff and RHK+ for F-, G-, and K-type
stars, respectively. We also confirm the dependence of both
chromospheric and photospheric activity on stellar rotation. Ca ii H
and K emissions and photospheric variations generally decrease with
increasing rotation periods for stars with rotation periods exceeding
a few days. The power-law indexes in exponential decay regimes show
different characteristics in the two activity-rotation relations. The
updated largest sample including the activity proxies and reported
rotation periods provides more information to understand the magnetic
activity for cool stars.
Description:
The LAMOST-Kepler project was initiated to use the LAMOST
spectroscopic survey to perform spectroscopic follow-up observations
for the targets in the field of the Kepler mission
(De Cat+, 2015, J/ApJS/220/19). By 2016 June, this project had
collected more than 180,000 optical spectra covering 3700-9000Å in
low-resolution R∼1800. In this work, we selected targets from the
LAMOST DR4.
We aim at targets of dwarfs, removing giant stars with an empirical
Teff-logg relation determined by Ciardi+ (2011AJ....141..108C 2011AJ....141..108C).
Binaries labeled by Berger+ (2018, J/ApJ/866/99) were also excluded.
To select F- to K-type stars, we use Teff in the range of 3800-7200K.
To place a lower limit on the quality of the individual observations,
the S/Ns at the blue end of the spectra are higher than 10. With these
constraints, we gathered 86689 spectra for 59816 stars.
We cross match 59816 stars with the catalog of McQuillan+
(2014, J/ApJS/211/24) and obtain 5575 targets with both photometric
observational data and spectroscopic observational data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 5575 Deduced activity proxies of the 5575 stars
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See also:
III/159 : Ca II H and K Measurements Made at MWO (Duncan+ 1991)
V/133 : Kepler Input Catalog (Kepler, 2009)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/ApJ/743/48 : Stellar rotation periods & X-ray luminosities (Wright+, 2011)
J/ApJ/781/124 : Granulation model for 508 KIC stars (Cranmer+, 2014)
J/A+A/572/A34 : Pulsating solar-like stars in Kepler (Garcia+, 2014)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)
J/MNRAS/448/822 : LAMOST candidate members of star clusters (Xiang+, 2015)
J/ApJ/834/207 : Periodicity of Kepler LCs variation (Mehrabi+, 2017)
J/ApJ/866/99 : Radii of KIC stars & planets using Gaia DR2 (Berger+, 2018)
J/ApJS/241/2 : Ionization profiles of 8 Galactic H II regions (Luisi+, 2019)
J/ApJS/243/28 : M star magnetic activities from LAMOST/Kepler (Lu+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC [1028018/12934451] Kepler Input Catalog ID
10- 16 F7.2 K Teff [3800/6639] Effective temperature (1)
18- 23 F6.2 K e_Teff [53/384] Uncertainty in Teff (1)
25- 28 F4.2 [cm/s2] log(g) [3.5/5.5] log surface gravity (1)
30- 33 F4.2 [cm/s2] e_log(g) [0/0.4] Uncertainty in log(g) (1)
35- 39 F5.2 [Sun] [Fe/H] [-2.8/0.5] Metallicity (1)
41- 44 F4.2 [Sun] e_[Fe/H] [0.06/0.3] Uncertainty in [Fe/H] (1)
46- 51 F6.4 [-] S [0.1/0.9] The S chromospheric index (2)
53- 58 F6.4 [-] e_S [0.0004/0.2] Uncertainty in S
60- 66 F7.4 [-] logR+HK [-7.3/-3.7] log R+HK chromospheric
index (3)
68- 73 F6.4 [-] e_logR+HK [0.001/0.4] Uncertainty in logR+HK
75- 82 F8.6 [-] Reff [9.8e-5/0.09] Effective photometic
variability amplitude (see Section 2.2)
84- 91 F8.6 [-] e_Reff [2e-6/0.02] Uncertainty in Reff
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Note (1): We use stellar atmospheric parameters (Teff, logg, and [Fe/H]) from
the LAMOST Stellar Parameter Pipeline at Peking University (LSP3;
Xiang+ 2015MNRAS.448..822X 2015MNRAS.448..822X).
Note (2): Following Karoff+ (2016NatCo...711058K 2016NatCo...711058K), we computed the flux ratio
S as the emission in the CaII H and K lines relative to the
continuum,
Equation (1): S=8α.(H+K)/(R+V)
where H and K are the fluxes integrated in 1.09Å FWHM triangular
windows centered on the line cores of 3968 and 3934Å. R and V are
the fluxes integrated in 20Å rectangular windows centered on
4001Å and 3901Å. The normalization factor α=1.8 was
adopted from Hall+ (2007AJ....133..862H 2007AJ....133..862H). The factor of 8 is the ratio
of exposure time between HK and RV channels of the Mount Wilson HKP-2
spectrophotometer. For stars with multiple observations, the S values
were calculated by the weighted mean values of these multiple spectra.
See section 2.1.1.
Note (3): Using Mittag+'s method (2013A&A...549A.117M 2013A&A...549A.117M), we calculated the
index RHK+ following
Equation (2):
RHK+=(FHK-FHK,phot-FHK,basal)/σTeff4=FHK+/σTeff4
where Teff is the effective temperature, and σ is the
Stefan-Boltzmann constant. Here the HK surface flux is derived from
the RV continuum flux and the S index through FHK=S.FRV/(8α)
(Middelkoop 1982A&A...107...31M 1982A&A...107...31M). The photospheric flux in the HK
bands FHK,phot, the basal chromospheric flux FHK,basal, and the
continuum flux FRV were calculated from the B-V color index
(Ramirez & Melendez 2005ApJ...626..465R 2005ApJ...626..465R).
See section 2.1.2.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Apr-2020